Zollinger-Ellison syndrome is a rare condition that causes severe ulcer disease in the stomach and duodenum (the first part of the small intestine). It also causes diarrhea.

This occurs due to a specific variety of tumor found in the pancreas or intestine. The tumor is a "gastrinoma."It manufactures the hormone "gastrin." Normally, gastrin stimulates the stomach to increase acid production in response to eating a meal. However, a gastrinoma keeps producing high levels of gastrin day and night. So, acid production in the stomach always remains above normal.

When there is a large amount of extra acid in the stomach, the acid can cause ulcers by irritating the lining of the stomach and duodenum. There is enough acid in this condition that acid can trickle to lower areas of the intestine than usual. Here it can cause irritation and neutralize the enzymes that usually help with your digestion, preventing the enzymes from having their desired effects. When this occurs, you can have difficulty absorbing your food and you can develop diarrhea.

If you have had peptic ulcers that don't heal well or that come back despite treatment, your doctor may decide to test for Zollinger-Ellison syndrome. A blood test to measure gastrin is usually the first step in testing.

To treat this syndrome, high-dose anti-acid medicine can be used. If the tumor that is making gastrin is found, it can usually be surgically removed.